In any milking herd, the detection of mastitis at an early stage, in any beast, is of the utmost importance.
It has for many years been known that the electrical conductivity of the milk taken from a cow gives an indication of the presence of mastitis, in that the electrical conductivity increases with increasing extent of infection. Electrical conductivity measuring cells for milking apparatus have been proposed, yet none is in common use at the present time. The usual method of detecting mastitis is by the detection of milk clots in milk passing through the milk line of individual cows being milked.
Commonly-used automatic milking apparatus uses a claw-piece having connections, by four short-milk tubes, to the four teat cups, for milking the four quarters of an individual cow. Connections to the claw-piece are provided from a pulsating vacuum source and a connection from the claw-piece is provided to the milk flow line. A continuous air-bleed is provided into the milk line on the upstream side of the claw-piece.
Recent study of the operation of such milking apparatus has disclosed that, in operation, milk from any one short-milk tube passes into the other three, so that the milk in any short-milk tube at any given time is not solely drawn from one quarter.
Mastitis, when it appears in a beast, normally appears first in one quarter, from which it may spread to the other quarters of the same beast and to other beasts of the herd. Consequently, early detection of mastitis means detection of mastitis in a single quarter. Yet, in present-day milking apparatus, there is no point in the system where solely milk from one quarter may be monitored.
This is believed, by the present inventor, to be one reason why monitoring by electrical conductivity has not been reliable nor found widespread use.
A further reason for unreliability of the method is the presence of air in the milk stream due to the air-bleed upstream of the claw-piece.
A second monitoring value of concern is the temperature of milk drawn from a cow, since this may give indication of sickness of a beast. However, again such measurement is rendered unreliable in present-day milking apparatus due, for example, to the introduction of cold air into the warm milk by reason of the continuous air-bleed.
A further monitoring value of importance is the volume, or weight, of milk drawn from each beast milked. It would be of value to know the quantity of milk drawn from each quarter and electrical flow-metering devices which might be fitted in the short-milk path are known. Yet with reverse-flow and the mixing of milk in the short-milk tubes, such measurement is not effective. Presently, milk volume is measured by recorder jars located in the long milk tube from each claw-piece.
Recently, however, there has been developed, and described in British patent specification No. 2,057,845, a claw-piece with integral valves, one at the connection of each short-milk tube. This claw-piece prevents the mixing of milk from one short-milk tube into another. Furthermore, it appears that this type of claw-piece is likely to come into widespread use for milking. Such an arrangement, preventing the mixing of milk from different quarters, is considered to be an essential feature of the present invention.
More recently, also, there has been developed, and described in British patent specification No. 8,512,941, a method of automatic milking, using such a valve claw-piece, wherein the introduction of air into the milk flow upstream of the valves is not permitted. This method is known as hydraulic milking and is regarded as a preferred feature of the present invention.
The object of this invention, therefore, is to provide monitor means for milking systems using the recent advances in milking technology mentioned above.
Accordingly, the present invention provides automatic milking apparatus comprising a claw-piece, a cluster of four short-milk tubes and associated teat cups for milking a cow's four quarters, a one-way valve system associated with the four short-milk tubes effective to prevent milk from one cow's quarter entering the short-milk tube of another quarter, a group of electrodes or electrical sensors associated with each of the four short-milk tubes, for continuously taking electrical measurement of a plurality of values relating to the milk passing through the related short-milk tube, switch means for selecting electrodes or sensors of the four groups for monitoring, a data processing unit for converting electrical signals in the various electrode or sensor circuits into meaningful values and display means for the visual display of such values.
Preferably, the said claw-piece and cluster operate without the introduction of air into the milk flow upstream of the valve system.
According to another aspect, the present invention provides a method of automatic milking of a cow's four quarters using a claw-piece and cluster of four short-milk tubes and teat cups, ensuring by valve means that milk from any one quarter does not enter the short-milk tube of another quarter, monitoring by electrical means a plurality of milk-related values for the milk flowing from all four quarters, selecting the values and quarter's milk to be monitored at any one time and providing a visual display of the values so monitored.